Mechanisms of platelet function alterations induced by low-intensity laser radiation

Abstract

Effects of laser radiation (wavelength 630 nm, power 1 roW) on platelet aggregation in human blood in vitro and in vivo and on platelet sensitivity to thromboxane A as well as on cyclooxygenase and thromboxane synthetase activities were studied. Changes in platelet functional activity were shown to be related to platelet transformation into inactive discoid form, suppression of their sensitivity to endogenous activators, and decreased activity of the arachidonic acid cascade enzymes. Key Words: blood; platelets; laser irradiationLow-intensity laser radiation produces a positive effect on microcirculation and on theological properties of the blood (suppression of the sludge phenomenon [7]) due to suppression of platelet function [1,8]. Platelet failure caused by laser rays results in the hypocoagulation syndrome [10]. All these factors increase the organic blood flow, in particular, in the case of vascular atherosclerotic lesions [5]. Modification of platelet function depends on the parameters of laser radiation [1]. Although the effects of laser radiation on platelet function have been thoroughly investigated, the mechanism of its action remains to be clarified.In the present work we studied mechanisms of the platelet function suppression produced by lowintensity laser radiation. MATERIALS AND METHODSBlood from 17 patients with nonspecific reactive hepatitis and 14 healthy volunteers was collected from the cubital vein in 3.8% sodium citrate. Donor's blood was permanently mixed and irradiated in vitro for 15 rain using an ALOK-1 laser (wavelength 630 nm, power 1 mW). In patients, in vivo blood irradiation in the cubital vein was performed through Department of Pharmacology and Department of Visceral Propedeutics, Volgogmd Medical Academy an intravenous light pipe. The same laser beam parameters were used. The 30-rain irradiations were repeated daily during a 5-day period. The blood was collected before and after the course of irradiation:Platelet-rich plasma was prepared according to [6]. Platelet aggregation was studied by the method [12] modified as in [2]. The kinetics of platelet aggregation was monitored with a 230LA dual-channel laser platelet aggregation analyzer (Biola Ltd., Russia). Platelets were activated with: ADP (5 gM, Serva), adrenaline hydrochloride (5 ~tM), platelet activating factor (0.01 gM, Sigma), collagen (4 ~tg/ml, Sigma), ristocetin (1.2 ~tg/ml, Sigma), and fibrinogen (3 g/l). The degree of platelet aggregation was expressed as percentage of light transmission. Aggregograms were analyzed suing an AGGR 2.20 (Biola) software [3]. Morphology and the number of platelets in aggregates were estimated with the Biola aggregation analyzer by the method [3].Platelet sensitivity to thromboxane A~ (Tx A2) , cyclooxygenase (COx) and thromboxane synthetase (TxS) activities were assessed indirectly in the tests with collagen (TxP h production inducer), aspirin (COx inhibitor), and imidasole (TxS inhibitor) by the method [4]. Platelet activity was assessed by changes in the mean size of aggregate.The resu...

Low-level light therapy reduces platelet destruction during extracorporeal circulation

“…LLLT inhibits PLT activation by such agonists as ADP, collagen, epinephrine, ristocetin, PAF, fibrinogen, adrenaline, ristomycin, and TRAP 17 , 37 – 39 . As such, irradiation most likely disrupts the activation processes of the coagulation system at a level common to all receptors.…”

Near-infrared photobiomodulation of blood reversibly inhibits platelet reactivity and reduces hemolysis

“…The reduction in spherical (activated) cells was accompanied by increased discoidal (non-activated) cells. This proves a decrease in the degree of their activation in the population of PLTs exposed to red light 34 , 35 .…”

“…Thus, blood clotting is reduced and the clot formation time is extended; the hypercoagulation syndrome is formed 33 . At the same time, no change in the total PLT count was observed 34 , 35 , 38 , but there has been a redistribution of the population’s shape. The reduction in spherical (activated) cells was accompanied by increased discoidal (non-activated) cells.…”

“…In the first case, PLT reversible dysfunction was noted—inhibition lasted 15 min, and fibrinogen rebinding occurred after 30 min 18 . In Spasov et al 34 , the sensitivity of irradiated PLTs to TxA2 and indirectly to the activities of COX and thromboxane synthetase (TxS) were determined. Collagen-activated PLTs were added to unmodified or irradiated PLTs, initiating aggregation-induced TxA2 production.…”